Apparatus for reducing interference



Sept. 2, 1930. P. GOLDSTONE 1,774,645

APPARATUS FOR REDUCING INTERFERENCE Filed July 30, 1927 4 Sheets-Sheet l v am/11 m I w anventoz l flliljf 50/08/0220 Maw e i Sepf. 2, 1930.

P. GCLDSTONE 1,774,645

I APPARATUS FOR REDUCING INTERFERENCE Filed July 30. 1927 4 Sheets-Sheet 2 112 f F i 1 1 13 Z Qwuwwtoz Sept. 2, 1830. P. GOLDSTONE APPARATUS FOR REDUCING INTERFERENCE Filed July :50, 1927 4 Sheets-Sheet 3 I I Z 41 V 212 1mm 2/2 I 411 x I 510 r l 512 i i; f 315 l 5 f Qwventoz 1%;! (in/dril Sept. 2, 1930.

P. sows-rows 1,774,545

APPARATUS FOR REDUCING INTERFERENCE Filed July 30.. 1927 4 Sheets-Sheet 4 L L L 414 441 W avwemtoz Finn ya midi/0120 @51 M flbto'vn Patented Sept. 2, 1930 ,UNITED STATES PATENT OFFICE PHILIP GOLDSTONE, OF WOODHAVEN, NEW YORK, ASSIGNOR TO GIBBS & HILL, OF NEW YORK, N. Y., A PARTNERSHIP OF NEW YORK APPARATUS FOR REDUCING INTERFERENCE Application filed July 30,

This invention relates to electric power transmission or distributing systems. More specifically it relates to alternating current transmission or distributing systems and has for one of its principal objects to provide a method and means for reducing the undesired inductive interference effect of such systems.

Certain of the objects of the invention are to provide improvements for certain classes of services. and under certain conditions of operation in the inventions disclosed and claimed in an application filed by me on September 10, 1921, and which is now United States Patent No. 1,564,345, patented D6CG1H- her 8, 1925. These and other objects and advantages will appear as the invention is hereinafter disclosed.

Referring to the drawings which illustrate what I now consider preferred forms which the present invention may assume Fig. 1 is a diagram illustrating the invention applied to a single section of a one track, single phase electric railway system.

Fig. 2 is a diagram for facilitating more detailed disclosure of the invention.

Figs. 3, 4, 5, 6 and 8 are views generally similar to F 1 but illustrating different forms of the invention.

Fig. 7 is a diagrammatic cross-section taken on the line 7-7 of Fig. 6.

\Vhile the invention may be applied to multi-track, or nullti-phase, or other systems, I have in order to avoid surplusage in illustration and description, shown it applied to a single section of a one track, single phase electric railway system. Referring first to Fig. 1 it will be seen that I have shown the usual high tension transmission or feeder conductors 10, 10 supplied with alternating current, at any desired voltage or frequency, through a step-up transformer 11. Stepdown transformers located at spaced substations or transformer stations are adapted to supply alternating propulsion current at a lower voltage to the contact conductor, shown as a trolley wire 12, and to the return conductor 13, shown as a track or ground return. of the railway. The primary wind I ings 14, 16 are shown connected across the 1927. Serial No. 209,445.

line 10, 10, the secondary windings 15, 17 being connected across the lines 12, 13. Each of the step-down transformers is provided with a secondary winding 17, each connected at one end or terminal to the grounded end of its adjacent secondary winding 15, 17. As thus far described the arrangement shown in Fig. 1 is generally the same as that shown in Fig. 1 of the above mentioned patent. However, the extra condoctor 19 shown in the patent is dispensed with and one or more of the high tension transmission conductors made to serve its purpose. lVhile the desired object may be obtained under certain conditions by con necting the ends of windings 15 and 17 to intermediate points of the primary windings of the transformers 14, 1G, I have shown, in Fig. 1, connections made to the ends of the said primaries or directly to one of the high tension conductors 10.

A balancing circuit is formed by the con ductor 10, coil 15, conductor 13, and coil 17 to perform the same or substantially the same function in reducing inductive interference as is performed by the conductor 19, coil 15', conductor 13, and coil 17 in the arrangement disclosed in the patent; It will be noted in the present arrangement that the conductor 10 serves in a dual capacity, i. e. as one of the conductors of the balancing circuit and also as one of the conductors of the high tension traiunnission line. This efiects greater economy since the conductor 19 (shown in the patent) is not only dispensed. with but also the breaker or protective equipment or appurtenances usually required for such a conductor.

In the use of system such that shown in 1 of the patent it is sometimes desirable to increase the voltage of the conductor 19 to a high value. but when this is done the balancing effect of the conductor 19 in compensating for the static effect of the condnctor 12 is not only more or less lost but if and when the voltage of the conductor 19 is made too great, it may have a detrimental effect by producing static induction in adja cent communication conductors. In the arrangement illustrated in present Fig. 1 the static effect of the is balanced by tl tie e'tiecix of the other 10 th s: two conduci -igh to: sion conduc 7 at eqn:

on O and 10 being a u l but opposite e itial. These two supply conductors l0 may conveniently be n'iaintained at it; OQPOSltG note itial by grounding the in of the Secondary of tie trznst s i art.

11 i a common gractice in the to it is believed that the foregoing d the art to d the now preterm: rorm n 1 out "he invention. shall describe t L. l and then retcr to some of the 1 J. lied forms which the invention condition to he attained with lanced tem that no current or Sil illy no curr nt shall How in the trolley circuit 12-13 when the load is coneenrail trated at on, and then the otlic: sulwtation thin condition is ate 1 and 2 (l and 2 in Fig. 1). hen

met, a load 1% or loads intermedi will prod stantially no n in a ien t 2 under intendec wn in l i analytically in which T renreeentn t-ea stations: 1 and 9: TP llcy rail circuit 12l -l hav- V r between station; 1 and 2: TF represent, halancine' circuit ha impedance Z ruin Z and Z", are the co rivalent impedancea the tranaformer' 11-:

t 7L, and Z, are the etmiialent imnedz'incesi ot the trim l t in: lil is he mutual wedance lictwe-en the circuits TR and TF: and

the nurtnal iznnc We l etween c T and all innxdances heinn; re n-es ented on trolle rail Yolta re hasia. It will lie horne in m nd tlizt t Tl? (l5'l0' l7l3l in c 'm'lnctor;

ch 5- e r to in wion an t '1 a Hill llto he coi 1 5 oven: 15-

is the inincoance iormer when missing: current tron.- the coil 1-2 to the coil 15 with the coil 15 open; and Z is the l nedance of the tr er (hen nee-sin can re 1 ion of coil) 1" and 1f 3 witn the coil 11 0 )en the transformer 1t 1T, 1T may similarly be derived.

Assuming a unit ampere load at station 2 and no current in the circuit TR, the current divisions are Shown by the arrows in Fig. 2. For the conoition of no current in the circuit TR, the voltage drop from oint 3 to point 2 by the path 3-l2, must he equal to the Voltage drop from the point- 3 to the point 2 by the path 2 -1-2, and the following relationship exists:

BI +Z 1 i may he found from the following equation:

For current satisfied is:

unit ampere load at station 1 and no in the circuit TR the conditlon to be 1' may he obtained from the following equation:

In order that- (5) and (0) may be satislied:

from which:

(l3 (Z Jig/'2' Z /i Substituting the values of i and i (Z4 Z M2) M2 424 +l113 Zt oulstituiing (1*) ant (7) in Equation 1Z3+ZI 1'+Z@::

ZH Z 4 which. the condition to be met.

In the form of invention shown in Fig. 3 the elements 110,111,112,113,114,115,115, 116, 117, and 117 correspond generally to the elements 1.0, 11, 12, 13, 14, 15, 15', 16, 17, and 17 respectively of Fig. 1. It will be noted, however, that additional windings 115 and 117" are provided corresponding generally to windings 115 and 117 the connections being as shown. In this case both high tension transmission wires 110, serve not only in that capacity or rOle but also as conductors of two balancing circuits. The one balancing circuit may be traced as follows: -110 (lower)--11'7113; and the other balancing circuit as follows 115110 (upper)117"112. This system may also be made to function by omitting the coils 14 and 16, as shown in Fig. 4. In this case the coils 115115 115' and 117117117 act as auto-transformers across the high ten sion transmission line 110110.

It will'be understood that in the arrangements of Figs. 3 and 4, as in the case of Fig. 1, the design is such that when the load is concentrated at station 1 there is no current or substantially no current in the trolley rail circuit, and when the load is concentrated at station 2 there is no current or substantially no current in the trolley rail circuit.

In Fig. 5 I have illustrated a somewhat different form of apparatus and connections operating in a somewhat diiferent way to re duce inductive interference. The elements 210, 210, 211, 212, 213, 214, 215, 216 and 217 will be recognized in view of generally similar elements shown in the preceding figures and require no further description. In addition there are provided transformer-coupled auxiliary conductors 212 and 213. The conductor 212 is connected to and extends between the trolley buses or trolley terminals of the secondaries 215 and 217. The conductor 213 is connected to and er:- tends between the ground or track terminals of the same secondary coils 215, 217. These two conductors 212 and 213 are coupled by means of a transformer whose primary 40 is in the conductor 212 and whose secondary is in the conductor 213. Any difference in potential between the secondaries 215 and 217 will cause a current (say I) to flow in the trolley conductor 212 and a current (say I) to flow in the conductor 212. The current I in conductor 212 is so stepped u by the transformer 40-41 that the current owing in the secondary coil 41, and consequently in the conductor 213', is equal in magnitude to the sum of the currents in the conductors 212 and 212','i. e. I plus I". This current in the conductor 213' (i. e. I plus I) completes its circuit through the track 213 but in an opposite direction to the current (1 plus I) tending to flow in the track circuit as a return path for the conductors 212 and The net effect is that substantially no current flows in the tracks due to unbalance of potential of the coils 215 and 217. The traction currents from an inter-station load return through the track to the adjacent substations 1,2, in opposite directions and as the ampere-miles between one substation and the load are equal to the ampere-miles between the other substation and the load, the effect of the traction currents on adjacent communication circuits extending between stations is cancelled out.

The design of the conductors 212, 213 and their coupling transformer 4041 is such that the current in the conductor 213 is substantially equal in value and in phase to the unbalanced currents in the conductors 212 and 212.

I wish to emphasize that while my inven tion has other important advantages, it is primarily designed to reduce undesired interference between power systems and adj acent systems which occupy the same or adjacent or more or less remote rights of way. To simplify illustration I have omitted, from each of Figs. 1, 3, 4 and 5, illustration of the conductors of such adjacent systems but it will be understood that they are present in conditions of actual practice, as shown for example as a telephone Wire in Figs. 6 and 8 to which I shall now refer.

In Figs. 6 and 7 I have illustrated a form of my invention in which undesired inductive interference is reduced and substantially eliminated in a manner specifically different from that employed in any of the forms of invention shown in Figs. 1, 3, 4 and 5. Referring to Figs. 6 and 7, it will be seen that the elements 310, 310, 311, 312, 313, 314, 315, 316 and 317, correspond respectively to the elements 10, 10', 11, 12, 13, 14, 15, 16 and 17, shown in Fig. 1; i. e. the system is shown as a single phase, single track, railway system. To facilitate explanation of the construction and operation of this (Figs. 6 and 7 form of the invention, it may be pointed out that the reason for most of the induction caused by a single phase electrification system upon another juxtaposed system, such as a telephone conductor C, is that the induction due to the contact conductor or trolley wire 312 is not equalized by the induction due to the return currents. The track 313 used as a return is, in practice, poorly insulated from the earth or ground G with the result that an appreciable percentage of current leaks off into the ground and returns by a path in the ground which is at a great distance from the telephone wire C as compared to the distance between the trolley wire and the telephone conductor C. In such case the induction from the trolley wire 312 upon the telephone conductor C is not neutralized by the induction from the track and ground return currents. In this form of my invention (Figs. 6 and 7), instead of employing the i teleohone conductor C of the )aths of the 1 l a mentioned currents, any otherwise unnced inductance upon the telephone conductor C is balanced out and substant'ally neutralized by toe inductive effect of the said conductor B.

in Fig. (3 the conductor B is shown suy plied with F. iii. by a secondary winding 315 of the transformer sir-s and a secondary winding 317' of the transformer 31(l3l7, connected as shown. l he number of turns and impedance of the windings 315 and 317' are such as to give the desired Y2 lue cnrrent through the wire B to effect ncutraliriation. or snbsiantially neutralize the inductive effect upon the telephone conductor C which would be. present if the conductor 13 (or some means as shown in Figs. 1, 3, i am /or 5, and described in connection ther with) r-sere not provider The form of invention shown in Figs. 6 and 7 vill give very satisfactory results in reducinginductive interference of the rail way system upon the telephone conductor when the design is such as to cause the following equation to be satisfied in which: I, is the current in each feeder wire 310, 310; the current in the trolley or contact conductor 312; L is the current in the track or j l; the current in the earth or ground in the neutralizing (ll' ltllllll 1J1: i 1, I135 I133 and i c t e 1 es letr *en the te ephone conductor and the other conduc ors ted 'n Fie T 11 former ll;0l-i1, and the telephone con .ructor C, will at one be recognized. In

w of the for going; d planations, it will be apparent that by proper design the form of iiventit :1 sho in in Fig. 8 may be caused to function and operate in sentially the same manner as that shown in Figs. 6 and 7. The system shown in Fig. 8 rar also be designed to embody some of the 7 characteristics of operation of thatshown in Fig. 5 and some of that shown in Figs. (5 and 7.

In accordance with the requirements of the patent statutes I have disclosed now preferred forms of my invention. It will be understood that the specific physical embodiments herein disclosed are illustrated only diagranunatically and, to avoid confusion and surplusage, more or less auxiliary apparatus such as circuit breakers switches etc., which may prove desirable in practice, have been omitted. However, with the present disclosure before him, a man skilled in the art to which the invention pertains could make and practice the invention. It is to be borne in mind also that while it is at present preferred to employ the anions features and elements in the combinations described, some of these may be altered and others omitted, and some of the features of each modification may be embodied in the others, without interferinowith the more general results and ellects outlined, and the invention extends to such use within the scope of the appended claims.

lVhat I claim is 1. An electrical system comprising in com hination, a supply circuit, a distribution circuit including a pluality of working conduct( rs, a plurality of transformers remotely loca"ed with respect to each other and havii'ig thei primary windings c nnected to said supply circuit and having points of their secondary windings connected to said supply circuit and working conductors, the windings of said transforn'iers being so related to said .:onductors and to each other to reduce the external inductive effect of the said distribution circuit to a negiig iljile alue.

2. An electrical all any system comprising a supply circuit, a distrilmtion circuit including: a trolley conductor and a track conductor; znd a plrrality of spaced transformers, each i primary connected across said supcirc lit. each having a secondary wind- 1 connected across said tro ley and track co id secondary wind ngr connected across one of said distribution conductors and one of the conductors of the supply circuit: the inmedances of the windings of said transformers being' so pro- POItlOll-Ctl relative to the impedances of said conductors and to each other that under a verage operating conditioi'is the .XtQlDtll inductive interference effect of said distribution circuit is substantially negl' 'ble.

3. An electrical railway sys em coxnynisinp a supply circuit, a distribution circuit including a trolley conductor and a track condn tor; and a plurality f spaced transformers, each having its primary connected across said supply circuit, each having a secondary winding connected across said trolley and track conductors, each having a secondary winding: connected across said trolley conductor and 2 ha wing it pl actors. and each having: a

lllf) one of the conductors of the supply circuit, and each having a seconding winding connected across the track conductor and another of the conductors of the supply circuit; the impedances of the windings of said transformers being so proportioned relative to the impedances of said conductors and to each other that under average operating conditions the external inductive interference effect of said distribution circuit is substantially negligible.

4. An electrical railway system comprising a supply circuit, a distribution circuit including a trolley conductor and a track conductor; and a plurality of spaced auto transformers each having its primary connected across said supply circuit, each having a secondary winding connected across said trolley and track conductors, each having a secondary winding connected across said trolley conductor and one of the conductors of the supply circuit, and each having a secondary winding connected across the track conductor and another of the conductors of the supply circuit; the impedances of the windings of said transformers being so proportioned relative to the impedances of said conductors and to each other that under average operating conditions the external inductive interference effect of said distribution circuitis substantially negligible.

5. A system, for reducing undesired interference between an A. C. railway system and juxtaposed conductors, comprising in combination, high tension supply conductors eX- tending along the route, lower tension contact and track conductors which receive propulsion energy from said supply conductors, spaced transformer windings connected in multiple with each other across said contact and return conductors, and means including one of said supply conductors for substan tially eliminating unbalanced track return currents.

6. A system, for reducing undesired interference between an A. C. railway system and juxtaposed conductors, comprising in combination, high tension supply conductors extending along the route, lower tension contact and track conductors which receive propulsion energy from said supply conductors, spaced transformer windings connected in multiple with each other across said contact and track conductors, and means including one of said supply conductors and transformer windings in addition to said first named transformer windings for substantial- ]y eliminating unbalanced track return currents.

7. A system, for reducing undesired interference between an A. C. railway system and juxtaposed conductors, comprising in combination, high tension supply conductors eX- tending along the route, lower tension contact and track conductors which receive propulsion energy from said supply conductors, spaced transformer windings connected in multiple with each other across said contact and track conductors, and means including, one of said supply conductors and transformer windings in addition to said first named transformer windings for substantially eliminating unbalanced track return currents without substantially changing the static effect of the supply conductors.

8. An electrical system comprising in co1nbination a supply circuit, a distribution circuit including a plurality of working conductors one of which is a track conductor, a plurality of transformers remotely located with respect to each other and having their primary windings connected to said supply circuit and their secondary windings connected to said working conductors, the point in each secondary winding which is connected to the track conductor being connected to an intermediate point in the primary winding associated with that secondary winding, the windings of said transformers being so related to said conductors and to each other as to reduce the external inductive effect of said distribution circuit to a negligible value.

In testimony whereof I hereto aliix my signature.

PHILIP GOLDSTONE. 

